1. Technical Field
The present invention relates generally to a method and apparatus for blocking fluid and fuel vapors. More particularly, the present invention relates to a unique method and construction of an apparatus for preventing fluid leakage and vapor migration through the use of electrical wires.
2. Discussion
Conventional automotive fuel delivery systems utilize an electric fuel pump mounted in a fuel tank to deliver fuel from the fuel tank to the engine. Power is supplied to the fuel pump through electric wires connected between the fuel pump and a voltage source such as an alternator or a vehicle battery. In order to reach the fuel pump, the electrical wires must pass through an opening in the fuel tank. Such an opening, unless properly sealed, potentially provides a pathway for fluid leakage and fluid vapor migration commonly referred to as vapor permeation. Minimizing such fluid leakage and vapor permeation is desirable due to increasing regulations regarding automotive fuel vapor emissions and overall product efficiency.
Several attempts to seal this opening in the fuel tank have been developed. Many of these contributions to the art include a bushing or a fitting adapted for placement in the opening. The electrical wires then pass through this bushing or fitting. Although the wires are fitted together as tightly as possible through the bushing or fitting, spaces or pores inevitably exist through which fluid leakage and vapor permeation is released.
In other contributions to the art, fluid leakage and vapor permeation is attempted to be prevented through the use of numerous continuous wires, the center portions of which are stripped of insulation. A plug is then placed over the exposed center insulation stripped wire portion. The entire composite is then blocked through a chemical bath treatment. Such a contribution is illustrated in U.S. Pat. No. 5,631,445 (Herster). Such contributions typically include production processes which are laborious and expensive, further possibly requiring separate internal and external harnesses. Moreover, the use of insulated continuous wire is rather costly and wasteful since this high end type of wire is only required in the area inside the fuel tank and not throughout the entire vehicle. Wires in the fuel tank are typically specially cured such as through chemical baths or through exposure to radiation to strengthen their various necessary attributes. This greatly increases the cost of the wires.
As set forth above, in order to maintain electrical integrity, the electrical wires are typically wrapped with expensive insulation. Some such wire insulation swells when exposed to fluid or vapor permeation which may cause cracking and/or breakage. Other types of insulation shrink when exposed to fluid or vapor permeation, thus increasing the size of the pathway through which fluid leakage or vapor permeation may escape. When the insulation on the wires passing through a fitting deteriorates due to shrinking or swelling, or when the wires are not sufficiently bound to the fitting, the area between the wire and the fitting are widened providing a greater pathway through which fluid leakage or vapor permeation may be released.
In other processes, the center of the conductors is stripped and through a vacuum process, a fuel resistant sealant is introduced to fill the pores between the wires and the fitting. New wire is also being developed which includes a blocking agent added during the extrusion process.
The current contributions to the art do not effectively compensate for the problems set forth above, in part by failing to adequately seal and close the space between the wires and the fitting, and by failing to sufficiently bond the wires to the fitting. In order to overcome the problems associated with the current contributions to the art, various designs and methods for blocking fluid and fuel vapors have been developed. The continued development has been directed to designs which simplify the manufacturing process and assembly while keeping costs at a minimum and performance at a maximum.